Dr. Ted Mosquin
Field of reference: Ecology, Biology
Description: On integrated systems of nature - symbiosis
"Symbiosis - Function 9
Symbiosis is the mutually beneficial, co-evolved association of a species with other (usually very unrelated) species. The degree of interdependency varies greatly. It may involve cooperation among three or more species. Symbiosis is one of the most powerful functions of the Ecosphere because as unrelated organisms began to depend on each other, wholly new kinds of life forms originated. There are tens of thousands of co-evolved symbiotic systems in all ecosystems in virtually all phyla (14). In the dawn of life symbiosis brought many submicrocopic organisms together permanently and, over eons, shaped the world of life as we know it today. In fact, all individual cells of "eucaryotes" (algae, protozoans, fungi, animals and plants) are permanent symbiotic systems, indicating that ecological functions operate even at the cellular level. The loss of any species, however small, may decrease the possibilities of new forms of symbiosis, and new life forms, tomorrow.
Mycorrhizal associations are widespread between fungal hyphae and vascular plant roots, in which fungi enable more efficient mineral absorption by the root hairs. In temperate forests some 80 to 90% of higher plants have roots associated with fungi.(15)
Lichens combine a green algae and/or a nitrogen fixing cyanobacteria with a fungal partner. The algae or cyanobacteria provide nutrients to the fungal host, and in return receive living space.(16) Some lichens contain both algal and cyanobacterial partners. Symbiotic associations are found between coelentrates and algae growing in their cells; between bacteria and echinoderms; between bacteria, protozoans and/or fungi living in the gut of animals (essential for food digestion); between ants and aphids, and ants and fungi.
Bioluminescence is the emission of cool chemical light by some groups of organisms such as plankton, many deep water fishes, some shallow water fishes, squids and fireflies. It is a unique kind of symbiosis. While in some cases the organism produces the light itself, in many species the light is emitted by phosphorescing bacteria which the host shelters and nourishes. In oceanic waters bioluminescence caused by bacteria occurs in fish species that live in the darkness up to 500 metres deep. For fish the light enables them to recognize species and mates (a form of communication), attract prey, camouflage their silhouettes from prey species through "countershading", and startle and distract predators.(18)
Symbiosis is also evident in pollination, in which an enormous variety of insects, birds and bats are adapted to pollinate tens of thousands of different species of flowering plants, and where plants have responded by evolving floral fragrances, reflectance spectra, flower forms, markings, and flowering-time sequences.
The biological complexity of pollination is underlined by the many forms that are mediated by the abiotic matrix of biodiversity, namely wind and water, both of which are the active agents of pollen transport between many plant species. In Canada, most trees, many shrubs, grasses, sedges, cattails and many forbs are wind pollinated. Water carries pollen in marsh plants such as the water shield,Brassenia schreberi, American eel grass, Vallisneria americana, the many species of Potamogeton, and others.
Impairment of many elements of symbiosis, through habitat fragmentation, pollution, pesticides, and other human activities has already caused extinction of thousands of races and species worldwide."
| שייך לנושאים: 1-13 - חינוך אינטגרלי, -מקורות מדעיים, הטבע, 2. הטבע כמערכת |
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